Treatment of drilling fluids



?atented Oct. 12, 1943 UNITD STATES orrlcn 2,331,282 TREATMENT OFDRELING FLS Truman B. Wayne, Houston, Tex.

6 Claims.

This invention relates generally to the treatment of mud-laden ordrilling fluids, and particularly to the treatment of such fluids as areemployed in the rotary drilling of oil and gas wells so as to improvethe physical properties of said fluids.

The fluid employed for rotary drilling operations may be made from thenatural clay which occurs at the location or may be syntheticallycompounded from the clay and mud bases of commerce, including bentoniteand beidellite. Such fluids may also contain a heavy substance such asbarytes, iron oxide, or the like, iorincreasing the specific gravity ofthe fluid.

Such fluids as are synthetically compounded may be controlled as toviscosity by a proper variation of the colloidal content, but when thecuttings from the bore hole become entrained in the fluid, itscomposition has changed, and further control is often necessary in orderto maintain the desired viscosity but at the same time to permit thecuttings to settle out and render the fluid of such character that itwill not be susceptible to gas cutting. With fluids which are compoundedwith the clay at the location, it is obvious that such control is morediflicult.

It is an object of the present invention, generally stated, to provide aprocess and agent for the treatment of mud-laden or drilling fluids inorder to control the viscosity and thixotropic properties thereof.

Another object of the invention is to provide a process and agent fortreating such fluids whereby the properties of the hydrated claycolloids are modified and the viscosity of the fluid reduced.

A further object of the invention is to provide a mud-laden or drillingfluid and the process of making it in which the properties of thecolloidal matter or gel constituent in the fluid are substantiallymodified and rendered suitable for rotary drilling purposes.

A more specific object of this invention is to provide a processandagent for the treatment of mud-laden or drilling fluids from a classof chemical reagents, and a treatment wherein a member of said class ofchemical reagents is used, and a drilling fluid which has been suitablymodified by said treatment, as will hereinafter be described.

Other objects will become apparent to those skilled in the art when thefollowing description is read.

In accordance with the present invention, generally stated, a mud-ladenfluid such as that employed in the rotary drilling of oil wells may betreated with a chemical agent which, upon reaction with certainconstituents of the fluid, modifies the colloidal properties of thecolloidal matter in the fluid. More specifically, in accordance with thepresent invention, the degelling action above-mentioned applications bythe fact that amino groups or substituted amino groups are additionallypresent in the molecule. The amino group is hydrophilic in character,and, aside from providing additional points in the complex moleculewherein a strongly hydrophilic phosphorus acid group may be introduced,it enhances the water-wettability and/or solubility of the molecule.

In illustration of this distinction, the phosphorus acid esters of anhydroxyanthraquinone would properly be classed with the substancescovered by my prior application, Serial No. 164,- 528, filed September18, 1937. However, generally, phosphorus acid esters ofhydroxyalkylaminoanthraquinones are preferred reagents, and improvementsin the processes of degelling mudladen or rotary drilling fluidsemploying such organic amino-phosphorous esters are claimed in thepresent application. Other similar nitrogenous organic esters ofphosphorus acids are also disclosed as suitable degelling agents in thepresent invention.

U. S. Patent N 0. 2,104,286 to Baumann disclosed the preparation of anumber of phosphorous or the hydroxyalkyl radical or radicals areattached to the aromatic nucleus through an'intervening amino residue.Compounds suitable for my purpose are'not restricted to this structureas the amino group or residue may suitably appear at other points in themolecule. The amino group or residue may be attached to the aromaticnucleus through an intervening ester radical or an intervening acylresidue, or by other means.

Suitable nitrogenous esters of ortho, meta, pyro, tetra, and other acidsof phosphorus are suitable. Esters or ether bodies prepared by analogousprocedure with phosphorus pentoxide are likewise contemplated. Theamino-substituted aromatic body may be an aromatic compound such asaminobenzene, amino-naphthalene, amino-anthracene, or other non-hydroxyaromatic body, or may be an amino-substituted-phenolic body such asamino-resorcinol, aminonaphthol, amino-pyrogallol, or otheramino-phenol. Amino derivatives of aromatic alcohols, aldehydes,ketones, quinones, etc., are likewise suitable. If inherently hydroxy,such as are the amino-phenols, they may be reacted without furthermodification with the phosphorus acid, anhydride, or halogenide to formthe nitrogenous esters of a phosphorus acid which are useful in thepresent invention. If non-hydroxy, or where further hydroxylation isdesirable, a suitable hydroxyalkylamino aromatic compound may bepreparedby reacting the aromatic amino compound with glycol monoanddi-chlorohydrins or the corresponding chlorohydrlns of glycerol or otherpolyhydric alcohols. This procedure is commonly carried out bydissolving the aromatic amino compound in a suitable inert solvent,adding the alkyl chlorohydrin, and refluxing until the reaction issubstantially complete. The mixture is then made strongly alkaline withsodium or potassium hydroxide and the amine layer removed. After dryingthoroughly, it may then be reacted with the phosphorus acid, anhydride,or halogenide in the manner disclosed either in Baumann Patent No.2,104,286, or in the examples which follow.

A second species of the general class of substances herein described as"nitrogenous organic esters of phosphorus acids are the phosphoric acidesters described in my copending application, Serial No. 152,275, datedJuly 6, 1937, disclosing and claiming such esters. These esters arecharacterized in the above-mentioned application as nitrogenoushydrophilic esters of a water-soluble polybasic acid or its chloride oranhydride, characterized by one or more ester radicals containing aresidue from a polyhydroxy body, and when the polybasic acid is aphosphorus acid the ester is a suitable member of the general class ofsubstances described in the present application as useful degellingagents for well drilling fluids.

In order to illustrate the principles of my invention, a number ofspecific examples are hereinafter given. However, it should bedistinctly understood that I do not confine myself to the specifictreating agents,.drilling fluid compositions or proportions hereinafterdisclosed, as it should be understood by those skilled in the art thatvariations from these disclosures do not depart from the principles andspirit of my invention which is directed in a general way to the use of"nitrogenous organic esters of phosphorus acids which are,hydrophilic incharacter and characterized by the pressure of one or more aminoresidues and one or more ester radicals containing a residue from ahydroxylated body, in the degelling and controlling of the viscosity ofmud-laden or rotary drilling fluids.

Exlmru: 1

Apolyphosphoric acid such as tetraphosphoric acid is reacted with analkylolamine such as triethanolamine, and the resulting compound is thenreacted with a polyhydroxy substance to form an ester. 338 parts oftetraphosphoric acid and an inert solvent such as triethyl phosphate,ortho-dichlorobenzene or trichlorobenzene are placed in a suitablevessel provided with cooling coils or jacket and parts of commercialtriethanolamine are slowly added while maintaining the temperature below50 C. 300 parts of powdered dry quebracho extract containingapproximately 72% of tannins are added and the mass is heated at C. fortwo hours. The finished product is a heavy, resinous, brown, tarrysubstance, fully soluble in water. It is freed of the inert solvent bydistillation and may be used as the acid mass, or after neutralizingwith soda, ammonia, or water soluble amine. Tests on a drilling mud areshown in Table 1.

EXAMPLE 2 A non-hydroxy alkylamine or cycloalkylamine is reacted withphosphoric acid, and the resulting salt or amide is reacted with apolyhydroxy substance to form an ester. As a specific example, 100 partsof cyclohexylamine are slowly added to 338 parts of tetraphosphoric acidwhile cooling to form the amine salt. Amide formation may occur athigher temperatures, and while this is not objectionable if the finalester has sufficient water solubility, no particular advantage resultsfrom amide formation at this stage. To the amine salt is added parts oftechnical pyrogallol, and the mass is stirred and heated at 100 to 200C. for several hours. An inert solvent may be used to carry out water ofreaction. The final product may be used in the unneutralized state, orany residual acidity may be neutralized with soda, ammonia, or a watersoluble amine. Tests on a drilling mud are shown in Table I.

EXAMPLE 3 A modification of Example 1 produces a product differingsomewhat in structure and properties. 300 parts of dry quebracho extractare dissolved in 140 parts of triethanolamine while stirring in a vesselequipped for stirring plastic masses. To the amine salt of thepolyphenolic quebracho compound are added 215 parts of 90% phosphoricacid and the mass is heated at 100-150 C. or higher, for four hours, oruntil a satisfactory degree of esteriflcation has been attained. Theplastic mass is fully soluble in water and may be used without furthertreatment, or may be neutralized with soda, ammonia, or a water solubleamine. Tests on a drilling mud are shown in Table I.

Tetraphosphoric acid is the preferred phosphoric acid in the abovesyntheses because of its anhydrous condition. Ordinary 85%orthophosphoric acid is preferably concentrated to at least 90% strengthbefore using, as esterification pro cedes with greater facility with themore anhydrous phosphoric acids, or their corresponding anhydrides.While these anhydrous forms of phosphoric acid are preferably used forthis reason, it is doubtless true that these and even glacialmetaphosphoric acid, if used, produce a final product containingconsiderable proportions of esters of orthophosphoric acid because waterformed during esterification is difiicult to remove from the mass evenwith an inert solviscosimeter, at 20-25 C.

Table I Propor- Volume of Initial Fina] source ester $2 gg g viscosityviscosity Grams Millililers Centipoises Cenlipoisea Example 1 0.10 10036 Do 0. 20 100 36 8 Example 2 0.10 100 36 18 Do. 0. 20 100 36 Example 30. 10 100 36 16 Do 0. 100 36 9 ExAMrm 4 A phosphorus acid ester ofl-hydroxyethylaminoanthraquinone, prepared according to Example 1 ofBaumann Patent No. 2,104,286, was used in the degelling of an aqueous 8per cent Wyoming bentonite drilling fluid having an initial viscosity ofcentipoises at 600 R. P. M. in a Stormer viscosimeter. Results obtainedthrough the use of varying proportions of this compound are tabulated inTable II.

EXAMPIIE 5 A phosphorus acid ester of1:4-dihydroxyethylaminoanthraquinone, prepared according to Example 2 ofBaumann Patent No. 2,104,286, was used in various proportions on otherportions of the same drilling fluid described in Example 4. Results aretabulated in Table II.

EXAMPLE 6 The same as Example 4, except that a phosphorus acid ester of1-hydroxyethylamine-4- bromoanthraquinone, prepared according to Example3 of Baumann Patent No. 2,104,286, was used. Results are tabulated inTable II.

Table II Viscosity in centipoises at various ratios (grams ofDhOSDilOl'llS'BCid ester per 100 Phosphorgsgcid ester ml. of drillingfluid) descn e m- Ori inal drilling fluid. 35 35 35 35 35 Exa mple 4. 2321 l9 l7 15 Example 5 23 19 19 17 15 Example 6 23 21 l9 l7 13 Theseesters may be used in any proportion ranging between 0.01 gram to 1.0gram per 100 ml. of drilling fluid, depending on the initial viscosityand other characteristics of the drilling fluid, as well as thecharactersticsdesired in the treated drilling fluid.

The preceding examples exemplify the use of my improved degellingagentson a normal mudladen drilling fluid prepared in the usual manner fromnatural or synthetic mud-making maassures 3 terlals. The relativelysmall proportions disclosed'are normally suflicient to obtain asatisfactory treatment. However, if it is desired to add largerquantities of gel-forming materials 5 such as bentonite, it is alsonecessary to-use larger proportions of the treating agent, usually from0.5 to 2.5 per cent, or even higher, based'on the'weight of the drillingfluid. The excess of treating agent reduces the gel-forming propertiesof the excess'bentonite or other material added, and thus allows largerproportions of, gelforming material to water than normally can beincorporated in the drilling fluid.

Wyoming bentonite was used with-water in viscosity of 36 centipoises intheStormer viscosimeter at 600 R. P. M., if the drilling fluid containsas much as 2 per cent of the treating agent, very much larger quantitiesofbentonite 30 may be incorporated without unduly increasing theviscosity. In fact, fluid muds may thus be prepared from bentonite whichapproximate the solids composition of muds prepared from naturalsources.

It is likewise obvious that muds which have become contaminated withcement, calcareous shales, and/or other sources of polyvalent metalcompounds which have produced abnormal viscosities, will require heaviertreatments with my 0 improved treating agent to produce normalviscosities for muds so contaminated. 7

While it is seldom necessary to use my improved degelling agents inconnection with other degelling agents, they may be used in conjunctionwith, or in admixture with, alkalies, tannins, al

kali tannates, inorganic phosphates, borates, silicates and/or othersubstances which have been proposed for this purpose.

The reagent may conveniently be added to the well drilling fluids in anyof the methods of addition commonly practiced, i. e., in the mudcirculating system in the ditches, sump, or at the pump suction. It maybe added in aqueous solution or in dry admixture with mud bases orweighting materials which commonly are added during the drillingoperation.

The reagent enibodying this invention is highly the anhydride is yieldedwhen the corresponding acid is dehydrated. Halogenides react directly toform the corresponding ester, and any remaining halogen atoms mayreadily be converted to compounding the drilling fluids used in theprethe corresponding phosphorus acid groups by hydrolysis.

While in the foregoing, theories are advanced, these are put forward tofacilitate the understanding of the objects and purp ses of thisinvention; it is to be understood, however, that this invention is notdependent upon or. limited to any theory put forward.

" What is claimed is:

1. The process of controlling the viscosity of an aqueous: mud-ladenwell-drilling fluid subject to viscosity variations, comprising, addingthereto a small proportion 01 a viscosity-reducing compound, whichcompound is a hydrophilic ester oi a phosphorus acid, characterized bythe presence therein of at least one amino residue from an amineselected from the group consisting of non-hydroxy alkyl, cycloalkvl,aralkyl, and aryl amines. and, at least one ester radical containing aresidue-from a hydroxy ,body or the aromatic series.

2. The process of controlling the viscosity of an aqueous mud-ladenwell-drilling fluid subject to viscosit variations, comprising. addingthereto a small proportion of a hydrophilic ester of a phosphorus acid,characterized by the pres"- ence therein of at least one amino residuefrom an amine selected from the group consisting of non-hydroxy alkyl,cycloalkyl, aralkyl, and aryl amines, and at least one ester radicalcontaining a residue from a polyhydroxy body of the arcmatic series.

3. An aqueous mud-laden well-drilling fluid subject to viscosityvariations, containing a relatively small proportion of aviscosity-reducing compound, which compound is a hydrophilic ester of aphosphorus acid, characterized by the presence therein of at least oneamino residue from an amine selected from the group consisting ofaccuses non-hydroxy alkyl, cycloalkyl, aralkyl, and aryl amines, and atleast one .ester radical containing a residue from a hydroxy body or thearomatic series.

4. The process of controlling the viscosity of an aqueous mud-ladenwell-drilling fluid subject to viscosity variations, comprising. addingthereto a small proportion 01' a viscosity-reducing compound;whichcompound is an ester of a polyphosphoric acid, characterized by thepresence therein or at least one amino residue from an amine selectedfrom the group consisting of nonhydroxy alkyl, cycloalkyl, arallryl, andaryl amines, and at least one ester radical containing a residue from ahydroxy body of thearomatic series.

5. An aqueous mud-laden well-drilling fluid subject to viscosityvariations, containing a relatively small proportion of aviscosity-reducing compound, which compound is a hydrophilic ester of apolyphosphoric acid, characterized by the presence therein of at leastone amino residue from an amine selected from the group consisting ofnon-hydroxy alkyl, cycloalkyl, aralkyl, and aryl amines, and at leastone ester radical containing a residue from a hydroxy body of thearomatic series.

6. An aqueous mud-laden well-drilling fluid subject to viscosityvariations, containing a relatively small proportion of aviscosity-reducing compound, which compound is a hydrophilic ester of aphosphorus acid, characterized by the presence therein of at least oneamino residue from an amine selected from the group consisting ofnon-hydroxy alkyl. cycloalkyl, aralkyl, and aryl amines, and at leastone ester radical containing a residue from a polyhydroxy body of thearomatic series.

TRUMAN B. WAYNE.

